Stability of polysomnography for one year and longer in children with sickle cell disease

Study Objectives: Serious morbidity may be linked to sleep disordered breathing (SDB) among children with sickle cell disease (SCD). We investigated the stability of polysomnography (PSG) results among children not having acute complications of SCD. Methods: Two PSGs were performed on a subsample of 63 children 4 to 18 years of age from the Sleep and Asthma Cohort Study. All had Hb SS or HbSβ0 disease. Two PSGs were compared for 45 subjects. Excluded from comparison were 18 children who had begun transfusions or hydroxyurea, had an adenotonsillectomy between the PSGs, or had a pain crisis or the acute chest syndrome within 3 months of the second PSG. Sleep disordered breathing was identifi ed using 2 thresholds for the apnea hypopnea index (AHI): ≥ 2 or ≥ 5 respiratory events per hour. Results: Ages were 12.3 yrs ± 4.0, BMI, 18.2 ± 3.2. Interval between PSGs was 581 ± 119 days (19.1 ± 3.9 months). Ten of 45 changed from ≥ 2 events per hour to < 2; 3 of 45 from < 2 to ≥ 2; 7 of 45 had ≥ 2 on both nights. Six of 45 changed from ≥ 5 to < 5, 2 of 45 from < 5 to ≥ 5, and 1 had ≥ 5 on both nights (McNemar χ², p = 0.09, and p = 0.29). Conclusions: In the absence of acute SCD complications, overnight PSG usually remains stable or improves over a 12- to 30-month period. Only 6.7% subjects, or fewer, had AHI on a subsequent PSG that would re-classify the child as having SDB not identifi ed in the earlier PSG.